NFS: Trace effects of the readdirplus heuristic

Enable tracking of when the readdirplus heuristic causes a page cache
invalidation.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 8b25a39..8a246df 100644 (file)
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1000,6 +1000,8 @@ static int find_and_lock_cache_page(struct nfs_readdir_descriptor *desc)
                        if (res == -EBADCOOKIE || res == -ENOTSYNC) {
                                invalidate_inode_pages2(desc->file->f_mapping);
                                desc->page_index = 0;
+                               trace_nfs_readdir_invalidate_cache_range(
+                                       inode, 0, MAX_LFS_FILESIZE);
                                return -EAGAIN;
                        }
                        return res;
@@ -1014,6 +1016,9 @@ static int find_and_lock_cache_page(struct nfs_readdir_descriptor *desc)
                        invalidate_inode_pages2_range(desc->file->f_mapping,
                                                      desc->page_index_max + 1,
                                                      -1);
+                       trace_nfs_readdir_invalidate_cache_range(
+                               inode, desc->page_index_max + 1,
+                               MAX_LFS_FILESIZE);
                }
        }
        res = nfs_readdir_search_array(desc);
@@ -1163,7 +1168,11 @@ static void nfs_readdir_handle_cache_misses(struct inode *inode,
        if (desc->ctx->pos == 0 ||
            cache_misses <= NFS_READDIR_CACHE_MISS_THRESHOLD)
                return;
-       invalidate_mapping_pages(inode->i_mapping, page_index + 1, -1);
+       if (invalidate_mapping_pages(inode->i_mapping, page_index + 1, -1) == 0)
+               return;
+       trace_nfs_readdir_invalidate_cache_range(
+               inode, (loff_t)(page_index + 1) << PAGE_SHIFT,
+               MAX_LFS_FILESIZE);
 }
 
 /* The file offset position represents the dirent entry number.  A

diff --git a/fs/nfs/nfstrace.h b/fs/nfs/nfstrace.h
index 7c1102b..ec2645d 100644 (file)
--- a/fs/nfs/nfstrace.h
+++ b/fs/nfs/nfstrace.h
@@ -273,6 +273,56 @@ DEFINE_NFS_UPDATE_SIZE_EVENT(wcc);
 DEFINE_NFS_UPDATE_SIZE_EVENT(update);
 DEFINE_NFS_UPDATE_SIZE_EVENT(grow);
 
+DECLARE_EVENT_CLASS(nfs_inode_range_event,
+               TP_PROTO(
+                       const struct inode *inode,
+                       loff_t range_start,
+                       loff_t range_end
+               ),
+
+               TP_ARGS(inode, range_start, range_end),
+
+               TP_STRUCT__entry(
+                       __field(dev_t, dev)
+                       __field(u32, fhandle)
+                       __field(u64, fileid)
+                       __field(u64, version)
+                       __field(loff_t, range_start)
+                       __field(loff_t, range_end)
+               ),
+
+               TP_fast_assign(
+                       const struct nfs_inode *nfsi = NFS_I(inode);
+
+                       __entry->dev = inode->i_sb->s_dev;
+                       __entry->fhandle = nfs_fhandle_hash(&nfsi->fh);
+                       __entry->fileid = nfsi->fileid;
+                       __entry->version = inode_peek_iversion_raw(inode);
+                       __entry->range_start = range_start;
+                       __entry->range_end = range_end;
+               ),
+
+               TP_printk(
+                       "fileid=%02x:%02x:%llu fhandle=0x%08x version=%llu "
+                       "range=[%lld, %lld]",
+                       MAJOR(__entry->dev), MINOR(__entry->dev),
+                       (unsigned long long)__entry->fileid,
+                       __entry->fhandle, __entry->version,
+                       __entry->range_start, __entry->range_end
+               )
+);
+
+#define DEFINE_NFS_INODE_RANGE_EVENT(name) \
+       DEFINE_EVENT(nfs_inode_range_event, name, \
+                       TP_PROTO( \
+                               const struct inode *inode, \
+                               loff_t range_start, \
+                               loff_t range_end \
+                       ), \
+                       TP_ARGS(inode, range_start, range_end))
+
+DEFINE_NFS_INODE_RANGE_EVENT(nfs_readdir_invalidate_cache_range);
+
 DECLARE_EVENT_CLASS(nfs_readdir_event,
                TP_PROTO(
                        const struct file *file,